212 THE PRINCIPLES OF HANDLING WOODLANDS 



other hand, the presence of a great number of small trees 

 increases the difficulty of felling the trees and making up 

 the wood, and offers a distinct hindrance to removing 

 the logs and wood. 



Practical Application of Thinnings in this Country. 

 The principles outlined in the preceding pages serve 

 as a guide for practise. In actual application they are 

 necessarily subject to considerable variation. The exact 

 measures to be used and the details of selecting the trees 

 must in every case depend on the requirements of the 

 given stand. The forester must diagnose the stand and 

 make the cuttings according to its peculiar needs. 

 Knowing the specific life characteristics and requirements 

 of the species and their capabilities under the given site 

 conditions, he makes his thinning so as to accomplish in 

 the highest measure the objects of management. 



As regards the time at which to begin the real thin- 

 nings Dr. Mayr specifies from the 30th to the 40th 

 years in the life of the stand. The statement means, 

 however, that this is an average for a stand well estab- 

 lished, in which the necessary work of cleaning in early 

 youth has already been made. It means also that this is 

 the period when thinnings ought ordinarily to begin. It 

 often happens even in Europe that it will not pay to make 

 thinnings even at 30 or 40 years of age, on account of 

 poor market and logging conditions. 



There are many instances of young mixed stands 

 in which valuable species are being badly crowded and 

 injured by those less valuable, and in the long run the 



